D. Douchanov et al., LOW-TEMPERATURE ASHING OF BULGARIAN LIGNITES, Erdol und Kohle, Erdgas, Petrochemie vereinigt mit Brennstoff-Chemie, 46(12), 1993, pp. 461-466
Citations number
43
Categorie Soggetti
Energy & Fuels","Engineering, Chemical",Geology,"Engineering, Petroleum
The characterisation of mineral components of coals requires their iso
lation from organic matter, which would otherwise interfere with phase
identification by means of physico-chemical techniques. Low-temperatu
re ashing (LTA) using a cool oxygen plasma is a prospective method to
oxidise coal organic matter at low temperatures while keeping the mine
ral constituents unaltered. In this work we have used a microwave-exci
ted plasma apparatus for the LTA treatment of lignite samples from the
Maritza-Iztok (M-I-1; M-I-2) and Elhovo basins. Minerals were charact
erised in the LTA residues using FT-IR spectroscopy, X-ray diffraction
and scanning electron microscopy combined with energy-dispersive X-ra
y microanalysis. The advantages and disadvantages of the LTA method ar
e discussed. Results indicate that LTA performs well for the isolation
of mineral matter, the ensuing methodology being adequate for the cha
racterisation of Bulgarian lignites. The same mineral constituents (pr
incipally clay minerals, quartz, pyrite and carbonates) were identifie
d in all the three studied samples, differences being mainly in their
particle size, degree of crystallinity and distribution in the organic
matter of coals.